Taisuke Sugaiwa

New visco-elastic mechanism design for flexible joint manipulator

We describe a space-efficient visco-elastic mechanism design for a small lightweight flexible joint of a human-symbiotic robot arm. Human-symbiotic robots that can provide daily life support will be required in houses, offices, facilities, and other places. Since they will often make physical contact with humans, their arms should have mechanical flexible joints to absorb the contact force and follow the humanpsilas motion. Our design has two coaxial rotary elements: a torsion bar made from GUMMETAL and a rotary disk damper with the output hole at its center. These two elements are combined in parallel and coaxially, making our design highly space-efficient. This paper presents the specifications of the shear elastic characteristics of GUMMETAL measured in experiments using 1DOF (degree-of-freedom) test equipment. The results confirm that its shear elastic modulus is linear and has a small elastic hysteresis loop and our mechanism can provide the advantage for the robot servo control. Compared with the conventional design, our design can make a smaller lighter flexible joint.

Shock absorbing skin design for human-symbiotic robot at the worst case collision

In this paper, we proposed a soft skin design method of human symbiotic robots which achieves collision safety in all collision situations. At the same time, soft skin design has to be optimized for the collision safety and the workability. Therefore we evaluate effectiveness of soft skin at each position on arm in longer-direction, and optimize its thickness along collision position. Firstly we discuss parameters for describing the collision between human and human-symbiotic robots, and identify the worst case collision including the out-of-control condition of the robots. Next we conducted actual collision experiments duplicating the worst case collision and apply the proposed method to soft skin covering of human-symbiotic robot ldquoTWENDY-ONErdquo. In consequence, TWENDY-ONE acquires both of collision safety and the workability.

A methodology for setting grasping force for picking up an object with unknown weight, friction, and stiffness

A methodology for setting the reference value of a grasping force when a multi-finger robotic hand grasps and lifts up an object without knowing its characteristic weight, coefficient of static friction, and stiffness was devised. The grasping force must be set to avoid dropping or deforming the object. To fulfill this requirement, the methodology measures object characteristics by detecting the moment of deformation or slipping according to the deflection of a mechanical passive element. The reference value of grasping force is set according to an upper limit to avoid crushing and a lower limit for lifting up the object calculated from the objects above-mentioned characteristics. The degree of the accuracy of object characteristic measurements was evaluated through experiments using an actual human-mimetic hand-arm system. Finally we validated that the system can pick up objects with the grasping force set by our methodology.

Dexterous hand-arm coordinated manipulation using active body-environment contact

Human-symbiotic humanoid robots that can perform tasks dexterously using their hands are needed in our homes, welfare facilities, and other places. To improve their task performance, we propose a motion control scheme aimed at appropriately coordinated hand and arm motions. By observing human manual tasks, we identified active body-environment contact as a kind of human manual skill and devised a motion control scheme based on it. We also analyzed the effectiveness of active body-environment contact in glass-placing and drawer-opening tasks. We validated our motion control scheme through actual tests on a prototype human-symbiotic humanoid robot.

Handling and grasp control with additional grasping point for dexterous manipulation of cylindrical tool

This study aims to construct a handling and grasp control method by multi-fingered robot hand with soft skin for the precision operation of cylindrical tools. We believe that the key to the improvement of the accuracy of the tool operation is to use an additional grasping point to reduce the tools posture fluctuation derived from the external force exerted at the tool nib. We focus two factors that cause the tools posture fluctuation. One is the rotation movement of the tool around the axis between two contacts by finger-tips. The other one is the deflection of the soft skin. We propose the effective allocation of the addition grasping point from the view point of the reduction of the tools posture fluctuation. Our control architecture is a customized combination of resolved motion rate control and hybrid control which maintains stable grasping and handles the tool along with the desired trajectory of the tool nib. It is validated through the physical tests using the actual multi-fingered robot hand that the accuracy of the tool nib trajectory is improved by proposed control method.

Motion-planning method with active body-environment contact for a hand-arm system including passive joints

Human-symbiotic humanoid robots that can perform tasks dexterously using their hands are needed in our homes, welfare facilities, and other places as the average age of the population increases. To improve the task performance of human-symbiotic humanoid robots, a motion-planning method with active body-environment contact was developed. Taking into account the positive and negative effect of mechanical passive elements implemented in joints, this motion-planning method can enables the hand-arm system to establish the active BE contact at the appropriate body-site and to select the joints that perform the movement for executing the given task. Control algorithms for the tool operation, namely, writing with a pen, were also constructed. The motion-planning method was validated through actual experiments on a prototype human-symbiotic humanoid robot.

A motion control for dexterous manipulation with human mimetic hand-arm system

Human-symbiotic humanoid robots that can perform tasks dexterously using their hands are needed in our homes, welfare facilities, and other places. To improve their task performance, we propose a motion control scheme aimed at appropriately coordinated hand and arm motions. By observing human manual tasks, we identified active body-environment contact as a kind of human manual skill and devised a motion control scheme based on it. We also analyzed the effectiveness of active body-environment contact in glass-placing and drawer-opening tasks. We validated our motion control scheme through actual tests on a prototype human-symbiotic humanoid robot.